diff --git a/RxSwift/Traits/PrimitiveSequence.swift b/RxSwift/Traits/PrimitiveSequence.swift
index 290d9cf39..4db796366 100644
--- a/RxSwift/Traits/PrimitiveSequence.swift
+++ b/RxSwift/Traits/PrimitiveSequence.swift
@@ -627,20 +627,6 @@ extension PrimitiveSequenceType where TraitType == MaybeTrait {
     }
 }
 
-extension PrimitiveSequence where Trait == CompletableTrait, Element == Never {
-    /**
-     Concatenates the second observable sequence to `self` upon successful termination of `self`.
-     
-     - seealso: [concat operator on reactivex.io](http://reactivex.io/documentation/operators/concat.html)
-     
-     - parameter second: Second observable sequence.
-     - returns: An observable sequence that contains the elements of `self`, followed by those of the second sequence.
-     */
-    public func concat(_ second: PrimitiveSequence<CompletableTrait, Never>) -> PrimitiveSequence<CompletableTrait, Never> {
-        return Completable.concat(self, second)
-    }
-}
-
 extension PrimitiveSequenceType where TraitType == CompletableTrait, ElementType == Never {
     /**
      Returns an empty observable sequence, using the specified scheduler to send out the single `Completed` message.
@@ -653,6 +639,18 @@ extension PrimitiveSequenceType where TraitType == CompletableTrait, ElementType
         return PrimitiveSequence(raw: Observable.empty())
     }
     
+    /**
+     Concatenates the second observable sequence to `self` upon successful termination of `self`.
+     
+     - seealso: [concat operator on reactivex.io](http://reactivex.io/documentation/operators/concat.html)
+     
+     - parameter second: Second observable sequence.
+     - returns: An observable sequence that contains the elements of `self`, followed by those of the second sequence.
+     */
+    public func concat(_ second: PrimitiveSequence<CompletableTrait, Never>) -> PrimitiveSequence<CompletableTrait, Never> {
+        return Completable.concat(primitiveSequence, second)
+    }
+    
     /**
      Concatenates all observable sequences in the given sequence, as long as the previous observable sequence terminated successfully.